• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1015-1022
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• 2012

This paper deals with hardware design which unifies MD5 and HAS-160 hash algorithms. Two algorithms get a message with arbitrary length and process message blocks divided into 512 bits each time and output a hash code with a fixed length. MD5 ouputs a hash code of 128 bits and HAS-160 a hash code of 160 bits. The unified hash core designed has 32% of slices overhead compared to HAS-160 core. However, there is only a fixed message buffer space used. The unified hash core which run a step in one clock cycle operates at 92MHz and has performance which digests a message in the speed of 724Mbps at MD5 and 581Mbps at HAS-160 hash mode. The unified hash core which is designed can be applicable to the areas such as E-commerce, data integrity and digital signature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1388-1393
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• 2007

The Microprocessor Based Laboratory Systems(MBL) with the remote access functional could put basic science experimental facilities together by providing a modem platform that the students can utilize simultaneously to learn basic physics, chemistry and biology, Our educator target platform combines a highly integrated 8-bit embedded Atmega128 processor and real time embedded OS (operating system), allowing plenty of headroom for follow-on basic science projects for students. The proposed MBL-NUTOS (Microprocessor Based Laboratory-NUT/OS) employed in the lab are available with internet base simulation capabilities, on public servers and students personal PCs, enabling the students to study at home and increasing the opportunity of accessing for the science laboratory facility.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.133-140
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• 2008

In this paper, we propose a high performance elliptic curve cryptographic processor over $GF(2^{163})$. The proposed architecture is based on a modified Lopez-Dahab elliptic curve point multiplication algorithm and uses Gaussian normal basis for $GF(2^{163})$ field arithmetic. To achieve a high throughput rates, we design two new word-level arithmetic units over $GF(2^{163})$ and derive a parallelized elliptic curve point doubling and point addition algorithm with uniform addressing based on the Lopez-Dahab method. We implement our design using Xilinx XC4VLX80 FPGA device which uses 24,263 slices and has a maximum frequency of 143MHz. Our design is roughly 4.8 times faster with 2 times increased hardware complexity compared with the previous hardware implementation proposed by Shu. et. al. Therefore, the proposed elliptic curve cryptographic processor is well suited to elliptic curve cryptosystems requiring high throughput rates such as network processors and web servers.

• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.133-140
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• 2004

Recently, the dental information systems were rapidly developed in order to store and process the data of patients. But, these systems should serve a doctor a good quality information against disease for diagnostic and surgery purpose so as to success in this field. This function of the system it important to persuade patients to undergo proper surgical operation they needed. Hence, 3D teeth model capable of simulating the dental surgery and treatment is necessary Teeth manipulation of dentistry is performed on individual tooth in dental clinic. io, 3D teeth reconstruction system should have the techniques of segmentation and 3D reconstruction adequate for individual tooth. In this paper, we propose the techniques of adaptive optimal segmentation to segment the individual area of tooth, and reconstruction method of tooth based on contour-based method. Each tooth can be segmented from neighboring teeth and alveolar bone in CT images using adaptive optimal threshold computed differently on tooth. Reconstruction of individual tooth using results of segmentation can be manipulated according to user's input and make the simulation of dental surgery and treatment possible.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.542-551
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• 2000

In this paper, a novel technique is presented for automatic brain region segmentation in single channel MR image data sets for 3D visualization and analysis. The method detects brain contours in 2D and 3D processing of four steps. The first and the second make a head mask and an initial brain mask by automatic thresholding using a curve fitting technique. The stage 3 reconstructs 3D volume of the initial brain mask by cubic interpolation and generates an intermediate brain mask using morphological operation and labeling of connected components. In the final step, the brain mask is refined by automatic thresholding using curve fitting. This algorithm is useful for fully automatic brain region segmentation of T1-weighted, T2-weighted, PD-weighted, SPGR MRI data sets without considering slice direction and covering a whole volume of a brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 in comparison with manual drawing in similarity index.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.340-347
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• 2005

This paper presents a polyphase down sampling based multiple description coding applied to H.264 video coding standard. For a given macroblock, a residual macroblock is calculated by motion estimation, and before applying DCT, quantization and entrophy coding of the H.264 coding process, the polyphase down sampling is applied to the residual macroblock to code in four separate descriptions. Experiments were performed for all the 9 test sequences of JVT SVC standardization in various packet loss patterns. Experimental results show that the proposed one gives 0.5 to 5 dB enhancement over an error-concealment based on the slice group map technolgoy.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.5
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• pp.530-539
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• 2002

Recently, there have been a lot of researches to develop an archive system for news videos that usually has a fixed structure. However, since the meta-data representation and storing schemes for news video are different from each other in the previously proposed archive systems, it was very hard to exchange these meta-data. This paper proposes a scheme for news video based on MPEG-7 MDS that is an international standard to represent the contents of multimedia, and a summarization mechanism reflecting the characteristics of shots in the news videos. The proposed scheme for news video uses the MPEG-7 MDS schemes such as VideoSegment and TextAnnotation to keep the original structure of news video, and the proposed summarization mechanism uses a slide-show style presentation of key frames with associated audio to reduce the data size of the summary video.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1925-1938
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• 2001

In this paper, a new block-matching algorithm for standard video encoder is presented. The slice competition method is proposed as a new scheme, as opposed to a coarse-to-fine approach. The order of calculating the SAD(Sum of Absolute Difference) to fad the best matching block is changed from a raster order to a dispersed one. Based on this scheme, the increasing SAD curve during its calculation is more linear than that of other curves. Then, the candidates of low probability can be removed in the early stage of calculation. And new MV prediction technique with an adaptive search range scheme also assists the proposed block-matching algorithm. As a result, an average of 13% improvement in computational power is recorded by only the proposed MV prediction technique. Synthetically, the computational power is reduced by 3977∼77% than that of the conventional BMAs. The average MAD is always low in various sequences. The results are also very close to the MAD of the full search block-matching algorithm.

• Journal of radiological science and technology
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• v.25 no.2
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• pp.83-83
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• 2002

국내 35개 병원의 44대의 CT장치를 대상으로 CT장치의 성능을 크게 7가지의 항목별로 구분하여 평가한 결과는 다음과 같았다. 물의 평균 CT number는 -18.9HU와 +68.6HU의 범위에 속했으며, 전체 장치의 평균은 $2.4{\pm}13.0\;HU$였다. 물의 평균 CT number의 권장수준을 -6과 +6로 하였을 경우 이에 적합한 장치는 35대(79.5%)였다. Contrast scale은 장치의 종류에 따라 많은 차이를 나타내었으나 평균은 $2.02{\pm}10^{-4}{\sim}1.665{\pm}10^{-5}$이었다. 직선성을 나타내는 상관계수는 0.984에서 0.992의 분포를 나타내었으며 평균은 $0.990{\pm}0.002$였다. 공간분해능은 0.60 m에서 1.25 mm의 분포를 나타내었으며 전체 장치의 65.9%에 해당되는 29대에서 0.75 mm의 공간 해상능을 나타내었다. 대조도 분해능은 3.2 mm(1/8인치)에서 19.1 mm(3/4인치)의 분포를 나타내었으며, 대조도 분해능의 권장수준을 6.4 mm 이하로 하였을 경우 측정 대상장치 44대 중 이에 적합한 장치는 37대(84.1%)였다. 슬라이스 두께의 설정치가 1 mm인 경우 측정치의 평균은 $2.0{\pm}0.6\;mm$이였으며, 설정치가 2 mm와 3 mm인 경우 측정치는 각각 $3.0{\pm}0.7\;mm$와 $3.5{\pm}0.6\;mm$이였다. 설정치가 5 mm와 7 mm인 경우 측정치는 각각 $5.1{\pm}0.6\;mm$, $7.0{\pm}0.5mm$이였다. 그리고 10 mm의 설정치에서는 $9.8{\pm}0.7\;mm$의 측정치를 나타내었다. 위치잡이용 중심선의 좌우방향의 편차는 -4.7 mm에서 +41.7 mm의 범위였으며, 상하방향의 편차는 -3.7 mm에서 +4.6 mm의 범위였다. 위치잡이용 중심선의 좌우 및 상하방향의 권장수준을 ${\pm}3.0\;mm$과 ${\pm}3.0\;mm$ 이하로 하였을 경우 41대의 측정 대상장치에서 이에 적합한 장치는 33대(80.5 %)였다.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.792-797
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• 1994

Force fields of syndiotactic isoregic PVF crystal have been extracted by optimizing a structure of 2,4,6-trifluoroheptane with ab initio Quantum mechanical method with 6-31G * * basis set, and applied to calculate the structure parameters and elastic constants of the material. The cell parameters turned out to be 5.205$\AA$, of a axis(chain axis), 8.457$\AA$, of b axis and 4.621$\AA$ of c axis. These parameters are in fair agreement with those of the atactic X-ray structure(5.04$\AA$, 8.57$\AA$, and 4.95$\AA$,respectively). The young's modulus of defect free syndiotactic PVF crystal was computed to be 267 GPa comparable to those of polyvinilidene fluoride(277-293 GPa) and polyethylene(264-337 GPa) crystals. Bulk modulus value obtained at optimum geometry is more than twice greater than that obtained at experimental geometry due to large difference of elastic compliance constant (especially Sgj element) at these two different geometries.